Rate of Dissolution of Silver in Aqueous Ceric Sulfate Solutions

1951 ◽  
Vol 98 (1) ◽  
pp. 31 ◽  
Author(s):  
Hugh W. Salzberg ◽  
Helen Knoetgen ◽  
Ann M. Molless
Keyword(s):  
Ceric Sulfate ◽  
Sulfate Solutions ◽  
Rate Of Dissolution

Precision standardization of ceric sulfate solutions

1968 ◽  
Vol 40 (1) ◽  
pp. 139-145 ◽  
Author(s):  
A. J. Zielen
Keyword(s):  
Ceric Sulfate ◽  
Sulfate Solutions

Mechanism of Pyrite Dissolution in the Presence ofThiobacillus ferrooxidans

1999 ◽  
Vol 65 (7) ◽  
pp. 2987-2993 ◽  
Author(s):  
T. A. Fowler ◽  
P. R. Holmes ◽  
F. K. Crundwell
Keyword(s):  
Redox Potential ◽  
Thiobacillus Ferrooxidans ◽  
Ferric Ions ◽  
Ferrous Ions ◽  
Bacterial Leaching ◽  
Experimental Conditions ◽  
Appl Environ ◽  
Sulfate Solutions ◽  
Rate Of Dissolution ◽  
Experimental Apparatus

ABSTRACT In spite of the environmental and commercial interests in the bacterial leaching of pyrite, two central questions have not been answered after more than 35 years of research: does Thiobacillus ferrooxidans enhance the rate of leaching above that achieved by ferric sulfate solutions under the same conditions, and if so, how do the bacteria affect such an enhancement? Experimental conditions of previous studies were such that the concentrations of ferric and ferrous ions changed substantially throughout the course of the experiments. This has made it difficult to interpret the data obtained from these previous works. The aim of this work was to answer these two questions by employing an experimental apparatus designed to maintain the concentrations in solution at a constant value. This was achieved by using the constant redox potential apparatus described previously (P. I. Harvey, and F. K. Crundwell, Appl. Environ. Microbiol. 63:2586–2592, 1997; T. A. Fowler, and F. K. Crundwell, Appl. Environ. Microbiol. 64:3570–3575, 1998). Experiments were conducted in both the presence and absence of T. ferrooxidans, maintaining the same conditions in solution. The rate of dissolution of pyrite with bacteria was higher than that without bacteria at the same concentrations of ferrous and ferric ions in solution. Analysis of the dependence of the rate of leaching on the concentration of ferric ions and on the pH, together with results obtained from electrochemical measurements, provided clear evidence that the higher rate of leaching with bacteria is due to the bacteria increasing the pH at the surface of the pyrite.

Physicochemical Characterization of Solid Dispersions of Cefdinir with PVP K-30 and PEG 4000

2010 ◽  
Vol 3 (2) ◽  
pp. 948-956
Author(s):  
Kumar P ◽  
S Kumar ◽  
A Kumar ◽  
M Chander
Keyword(s):  
Solid Dispersions ◽  
Physicochemical Characterization ◽  
Drug Carriers ◽  
Dissolution Properties ◽  
Rate Of Dissolution ◽  
Peg 4000 ◽  
Release Studies ◽  
Crystalline Nature ◽  
Physical Mixtures

The purpose of this study was to prepare and characterize solid dispersions of the antibacterial agent Cefdinir with PEG 4000 and PVP K-30 with a view to improve its dissolution properties. Investigations of the properties of the dispersions were performed using release studies, X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR). The results obtained showed that the rate of dissolution of Cefdinir was considerably improved when formulated in solid dispersions with PVP K-30 and PEG 4000 as compared with pure drug and physical mixtures. The results from XRD studies showed the transition of crystalline nature of drug to amorphous form, while FTIR studies demonstrated the absence of drug-carriers interaction.

Formulation and Evaluation of Nanosuspension of Simvastatin

2015 ◽  
Vol 8 (2) ◽  
pp. 2858-2873
Author(s):  
Rupali L. Shid ◽  
Shashikant N. Dhole ◽  
Nilesh Kulkarni ◽  
Santosh L Shid
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Factorial Design ◽  
Dissolution Rate ◽  
In Vitro Dissolution ◽  
Total Drug ◽  
23 Factorial Design ◽  
Rate Of Dissolution

Poor water solubility and slow dissolution rate are issues for the majority of upcoming and existing biologically active compounds. Simvastatin is poorly water-soluble drug and its bioavailability is very low from its crystalline form. The purpose of this study wasto increase the solubility and dissolution rate of simvastatin by the  preparation of nanosuspension by emulsification solvent diffusion method at laboratory scale. Prepared nanosus-pension was evaluated for its particle size and in vitro dissolution study and characterized by zeta potential,differential scanning calorimetry (DSC) and X-Ray diffractometry (XRD), motic digital microscopy, entrapment efficiency, total drug content, saturated solubility study and in vivo study. A 23 factorial design was employed to study the effect of independent variables, amount of SLS (X1), amount of PVPK-30 (X2) and poloxamer-188 (X3) and dependent variables are total drug content and polydispersity Index. The obtained results showed that particle size (nm) and rate of dissolution has been improved when nanosuspension prepared with the higherconcentration of PVPK-30 with the higher concentration of PVP K-30 and Poloxamer-188 and lower concentration of SLS. The particle size and zeta potential of optimized formulation was found to be 258.3 nm and 23.43. The rate of dissolution of the optimized nanosuspension was enhanced (90% in 60min), relative to plain simvastatin  (21% in 60 min), mainly due to the formation of nanosized particles. These results indicate the suitability of 23 factorial  design for preparation of simvastatin loaded nano-suspension significantly improved in vitro dissolution rate and thus possibly enhance fast onset of therapeutic drug effect. In vivo study shows increase in bioavailability in nanosuspension formulation than the plain simvastatin drug.

Enhanced oral bioavailability of Etodolac by liquisolid compact technique: optimisation, in-vitro and in-vivo evaluation

2020 ◽  
Vol 17 ◽  
Author(s):  
Bhumin K. Pathak ◽  
Meenakshi Raghav ◽  
Arti R. Thakkar ◽  
Bhavin A. Vyas ◽  
Pranav J. Shah
Keyword(s):  
Dissolution Rate ◽  
Amorphous State ◽  
Immediate Release ◽  
Angle Of Repose ◽  
Oral Suspension ◽  
Load Factor ◽  
In Vivo Evaluation ◽  
Rate Of Dissolution ◽  
Q 30

Background: Poor dissolution of Etodolac is one of the major challenges in achieving the desired therapeutic effect in oral therapy. Objective: This study aimed to assess the potential of liquisolid compact technique in increasing the rate of dissolution of Etodolac and thus its bioavailability. Methods: Liquisolid compacts were prepared using PEG 400, Avicel PH-200 and Aerosil 200 as non-volatile liquid, carrier and coating material respectively. Optimisation was carried out by applying a 32 full factorial design using Design expert software 11.0.3.0 to examine the effects of independent variables (load factor and carrier: coating ratio) on dependent variables (angle of repose and % cumulative drug release at 30 min [Q 30 min]).Assessment of bioavailability was based on pharmacokinetic study in rabbits and pharmacodynamics evaluation in rats respectively. Results: The formulation M3 was identified as the optimised formulation based on the better flow (lower angle of repose) and a higher rate of dissolution (Q 30 min >95%). The higher dissolution rate could be due to conversion of Etodolac into an amorphous molecularly dispersed state, availability of larger surface area, enhancement of aqueous solubility and enhanced wetting of drug particles. Studies with DSC, XRD, and SEM verified the transformation of Etodolac from crystalline to amorphous state, a key factor responsible for improving the dissolution rate. Pharmacokinetic profile of M3 was prominent, demonstrating higher absorption of Etodolac in comparison of oral suspension and immediate-release conventional tablets in rabbits. Liquisolid formulation exhibited 27% increment in paw thickness as compared to 57% and 46% increments for oral suspension and immediate-release conventional tablets respectively, after 7 hrs in carrageenan-induced paw model in rats. Conclusion: The results indicated liquisolid compact technique to be a promising strategy to enhance the bioavailability of Etodolac.

Codeposition of copper and tin from acidic sulfate solutions containing polyethylene glycols. Effect of length of the hydrocarbon chain

2008 ◽  
Vol 14 (4) ◽  
pp. 507-514 ◽  
Author(s):  
Arvydas Survila ◽  
Dalia Bražinskienė ◽  
Stasė Kanapeckaitė ◽  
Zenius Mockus ◽  
Vitalija Jasulaitienė
Keyword(s):  
Hydrocarbon Chain ◽  
Polyethylene Glycols ◽  
Sulfate Solutions ◽  
Acidic Sulfate
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